Search Publications
A High Angular Resolution Survey of Massive Stars in Cygnus OB2: Results from the Hubble Space Telescope Fine Guidance Sensors
Herrero, A.; Gies, D. R.; Moffat, A. F. J. +8 more
We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the fine guidance sensor 1R (FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems with a magnitude difference ΔV < 4 down to separations as small as 0.''01. The sample includes 58 of the bright…
Prospects for Measuring Supermassive Black Hole Masses with Future Extremely Large Telescopes
Barth, Aaron J.; Do, Tuan; Larkin, James E. +6 more
The next generation of giant-segmented mirror telescopes (>20 m) will enable us to observe galactic nuclei at much higher angular resolution and sensitivity than ever before. These capabilities will introduce a revolutionary shift in our understanding of the origin and evolution of supermassive black holes by enabling more precise black hole ma…
A CO Survey in Planet-forming Disks: Characterizing the Gas Content in the Epoch of Planet Formation
Ménard, F.; Casassus, S.; Eiroa, C. +13 more
We carried out a 12CO(3-2) survey of 52 southern stars with a wide range of IR excesses (L IR/L *) using the single-dish telescopes APEX and ASTE. The main aims were (1) to characterize the evolution of molecular gas in circumstellar disks using L IR/L * values as a proxy of disk dust evolutio…
Astrometrically Registered Simultaneous Observations of the 22 GHz H2O and 43 GHz SiO Masers toward R Leonis Minoris Using KVN and Source/Frequency Phase Referencing
Byun, Do-Young; Kim, Jongsoo; Kim, Kee-Tae +22 more
Oxygen-rich asymptotic giant branch (AGB) stars can be intense emitters of SiO (v = 1 and 2, J = 1 → 0) and H2O maser lines at 43 and 22 GHz, respectively. Very long baseline interferometry (VLBI) observations of the maser emission provide a unique tool to probe the innermost layers of the circumstellar envelopes in AGB stars. Neverthel…
The Solar Neighborhood. XXXI. Discovery of an Unusual Red+White Dwarf Binary at ~25 pc via Astrometry and UV Imaging
Gies, Douglas R.; Henry, Todd J.; Winters, Jennifer G. +4 more
We report the discovery of a nearby M5.0V dwarf at 24.6 pc, SCR 1848-6855, that is orbited by an unusual companion causing an astrometric perturbation of more than 200 mas. This is by far the largest perturbation found to date among more than 700 targets observed during our long-term astrometry/photometry program at the CTIO 0.9 m telescope. We pr…
Radio-Optical Reference Frame Link Using the U.S. Naval Observatory Astrograph and Deep CCD Imaging
Zacharias, N.; Zacharias, M. I.
Between 1997 and 2004 several observing runs were conducted, mainly with the CTIO 0.9 m, to image International Celestial Reference Frame (ICRF) counterparts (mostly QSOs) in order to determine accurate optical positions. Contemporary to these deep CCD images, the same fields were observed with the U.S. Naval Observatory astrograph in the same ban…
Close Companions to Two High-redshift Quasars
Strauss, Michael A.; Fan, Xiaohui; Jiang, Linhua +5 more
We report the serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z = 4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit spectroscopy shows excess Lyα emission extending well beyond the quasar's light profile. Further imaging and spectro…
The SLUGGS Survey: HST/ACS Mosaic Imaging of the NGC 3115 Globular Cluster System
Romanowsky, Aaron J.; Brodie, Jean P.; Strader, Jay +6 more
We present Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) g and z photometry and half-light radii R h measurements of 360 globular cluster (GC) candidates around the nearby S0 galaxy NGC 3115. We also include Subaru/Suprime-Cam g, r, and i photometry of 421 additional candidates. The well-established color bimodality of th…
Extra-nuclear Starbursts: Young Luminous Hinge Clumps in Interacting Galaxies
Soria, Roberto; Swartz, Douglas A.; Struck, Curtis +3 more
Hinge clumps are luminous knots of star formation near the base of tidal features in some interacting galaxies. We use archival Hubble Space Telescope (HST) UV/optical/IR images and Chandra X-ray maps along with Galaxy Evolution Explorer UV, Spitzer IR, and ground-based optical/near-IR images to investigate the star forming properties in a sample …
The Snapshot Hubble U-Band Cluster Survey (SHUCS). II. The Star Cluster Population of NGC 2997
Larsen, S.; Bastian, N.; Smith, L. J. +6 more
We study the star cluster population of NGC 2997, a giant spiral galaxy located at 9.5 Mpc and targeted by the Snapshot Hubble U-band Cluster Survey (SHUCS). Combining our U-band imaging from SHUCS with archival BVI imaging from the Hubble Space Telescope, we select a high confidence sample of clusters in the circumnuclear ring and disk through a …